Scroll compressor

ABSTRACT

In a scroll compressor according to the present invention, at least one injection port penetrating a second end plate of a fixed scroll at a position where the injection port is open to a first compression chamber or a second compression chamber in a compression stroke after the suction refrigerant is introduced and closed. Further, the discharge bypass port is disposed such that a volume ratio, which is a ratio of a suction volume to a discharge volume of the second compression chamber at which the refrigerant in the first compression chamber can be discharged, is smaller in the first compression chamber, which is one compression chamber having the large amount of the refrigerant injected from the injection port, than in the second compression chamber, which is the other compression chamber among the first compression chamber and the second compression chamber.

TECHNICAL FIELD

The present invention relates to a scroll compressor particularly used for a refrigeration machine such as an air conditioner, a water heater, and a refrigerator.

BACKGROUND ART

In a refrigeration apparatus and an air conditioner, a compressor is used which sucks a gas refrigerant evaporated by an evaporator, compresses the gas refrigerant to a pressure required for condensation by a condenser, and sends high-temperature high-pressure gas refrigerant to a refrigerant circuit. Thus, a scroll compressor is provided with two expansion valves between the condenser and the evaporator and injects an intermediate-pressure refrigerant flowing between the two expansion valves to a compression chamber during a compression process, thereby aiming to reduce power consumption and improve capacity of a refrigeration cycle.

That is, the refrigerant circulating in the condenser is increased by the amount of the injected refrigerant. In the air conditioner, heating capacitor is improved. Further, since the injected refrigerant is in an intermediate pressure state, and power required for compression ranges from the intermediate pressure to the high pressure, a coefficient of performance (COP) can be improved and power consumption can be reduced, as compared to a case where the same function is provided without injection.

The amount of the refrigerant flowing in the condenser is equal to a sum of the amount of the refrigerant flowing in the evaporator and the amount of the injected refrigerant, and a ratio of the amount of the injected refrigerant to the amount of the refrigerant flowing in the condenser is an injection rate.

To increase an effect of injection, the injection rate may increase. Thus, the refrigerant is injected due to a pressure difference between the pressure of the injected refrigerant and the internal pressure of a compression chamber. To increase the injection rate, it is necessary to increase the pressure of the injected refrigerant.

However, when the pressure of the injected refrigerant increases, a liquid refrigerant is injected to the compression chamber, which causes a decrease in heating capacity and a decrease in reliability of the compressor.

In the refrigerant introduced into the compression chamber from an injection pipe, the gas refrigerant is preferentially extracted from a gas-liquid separator and is fed. However, when balance of intermediate pressure control is broken or when a transient condition is changed, in a state in which the liquid refrigerant is mixed with the gas refrigerant, the mixture is introduced from the injection pipe. In the compression chamber having many sliding parts, in order to keep a sliding state good, an appropriate amount of oil is fed and is compressed together with the refrigerant. However, when the liquid refrigerant is mixed, the oil in the compression chamber is washed by the liquid refrigerant. Thus, the sliding state deteriorates, components are worn or burned. Thus, it is important that the liquid refrigerant introduced from the injection pipe is not fed to the compression chamber as far as possible and only the gas refrigerant is guided to an injection port.

The intermediate pressure is controlled by adjusting an opening degree of the expansion valves respectively provided upstream or downstream of the gas-liquid separator, and an injected refrigerant is fed into the compression chamber by a pressure difference between the intermediate pressure and the internal pressure of the compression chamber in the compressor to which the injection pipe is finally connected. Therefore, when the intermediate pressure is adjusted high, the injection rate increases. Meanwhile, the higher the intermediate pressure, the smaller a gas-phase component ratio of the refrigerant flowing from the condenser via the upstream expansion valve to the gas-liquid separator. Thus, when the intermediate pressure excessively increases, the liquid refrigerant in the gas-liquid separator increases, and the liquid refrigerant flows into the injection pipe, resulting in a decrease in heating capacity and a decrease in reliability of the compressor.

Thus, a configuration which obtains a large amount of the injected refrigerant using the intermediate pressure as low as possible is desirable as the compressor, and a scroll type having a slow compression rate is suitable as a compression method.

In particular, a symmetric scroll compressor in which compression chambers having the same volume are formed at the same timing outside and inside a wrap of the orbiting scroll has a feature in which mechanical balance is excellent in a low vibration state due to symmetry of the compression chambers. Thus, the scroll compressor has been used for various fields such as air conditioning.

Meanwhile, regarding the injection, in the scroll compressor according to the related art, opening ranges of the injection port and the bypass port are disclosed (see, for example, PTL 1). Accordingly, the scroll compressor is provided which can cope with various operation modes including the injection with high performance.

CITATION LIST Patent Literature

PTL 1: Japanese Patent No. 3764261

SUMMARY OF THE INVENTION

In the symmetric scroll compressor, a compression start timing of a first compression chamber formed outside a wrap of the orbiting scroll and a compression start timing of a second compression chamber formed inside the wrap of the orbiting scroll are equal to each other. Thus, it is difficult for one injection port to always send the same amount of the injected refrigerant to the first compression chamber and the second compression chamber.

Further, in PTL 1, a relationship between opening sections of the bypass port and the injection port is disclosed. However, a relationship between the amount of injection to the first compression chamber and the second compression chamber and the bypass port is not disclosed.

The present invention relates to a scroll compressor that can prevent an excessive compression operation due to a difference between injection amounts occurring in a symmetric scroll compressor, can cope with the operation even at a higher injection rate to maximize an original effect of an injection cycle, and can expand a capacity improvement amount.

The scroll compressor according to the present invention includes a fixed scroll including a first spiral wrap standing up from a first end plate of the fixed scroll and an orbiting scroll including a second spiral wrap standing up from a second end plate of the orbiting scroll, wherein the first spiral wrap of the fixed scroll is engaged with the second spiral wrap of the orbiting scroll to define a compression chamber between the fixed scroll and the orbiting scroll. Further, the compression chamber includes a first compression chamber on an outer wall side of the second spiral wrap of the orbiting scroll and a second compression chamber on an inner wall side of the second spiral wrap of the orbiting scroll, the suction volume of the first compression chamber is substantially equal to the suction volume of the second compression chamber. Further, the first end plate of the fixed scroll includes a central portion having a discharge port through which a refrigerant compressed in the compression chamber is discharged. The scroll compressor further comprises a discharge bypass port through which the refrigerant compressed in the compression chamber is discharged before the compression chamber communicates with the discharge port is provided. Further, the scroll compressor comprises at least one injection port through which an intermediate-pressure refrigerant is injected into the first compression chamber, the at least one injection port penetrating the first end plate of the fixed scroll at a position where the injection port is open to the first compression chamber or the second compression chamber during a compression stroke after a suction refrigerant is introduced and closed. Further, the scroll compressor comprises the discharge bypass port is disposed such that a volume ratio is smaller in one compression chamber of the first compression chamber and the second compression chamber, which has the large amount of the refrigerant injected from the injection port, than in the other compression chamber, the volume ratio of the suction volume to the discharge volume of the compression chamber at which the refrigerant in the compression chamber can be discharged.

In this way, as more injection is injected into a compression chamber having a small volume ratio, an injection rate increases, so that an effect of an injection cycle can be maximized, and efficiency improvement and capacity expansion effect can be obtained more than the related art.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a refrigeration cycle including a scroll compressor according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the scroll compressor according to the first embodiment of the present invention.

FIG. 3 is an enlarged view showing a main part of FIG. 2.

FIG. 4 is a view taken along line 4-4 of FIG. 3.

FIG. 5 is a view taken along line 5-5 of FIG. 4.

FIG. 6 is a view taken along line 6-6 of FIG. 3.

FIG. 7 is a graph showing an internal pressure of the compression chamber of the scroll compressor when an injection operation is not accompanied.

FIG. 8 is a diagram for illustrating a positional relationship between an oil supplying passage and a sealing member accompanying an orbiting movement of the scroll compressor according to the first embodiment of the present invention.

FIG. 9 is a diagram for illustrating an opening state of the oil supplying passage and an injection port accompanying the orbiting movement of the scroll compressor according to the first embodiment of the present invention.

FIG. 10 is a longitudinal sectional view showing a scroll compressor according to a second embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinafter, a scroll compressor according to a first embodiment of the present invention will be described. The present invention is not limited to the following present embodiments.

FIG. 1 is a diagram showing a refrigeration cycle including the scroll compressor according to the first embodiment.

As illustrated in FIG. 1, a refrigeration cycle device including the scroll compressor according to the present embodiment includes compressor 91 that is the scroll compressor, condenser 92, evaporator 93, expansion valves 94 a and 94 b, injection pipe 95, and gas-liquid separator 96.

A refrigerant, which is a working fluid condensed by condenser 92, is depressurized to an intermediate pressure by expansion valve 94 a on an upstream side, and gas-liquid separator 96 separates the refrigerant at the intermediate pressure into a gas-phase component (a gas refrigerant) and a liquid-phase component (a liquid refrigerant). The liquid refrigerant depressurized to the intermediate pressure further passes through expansion valve 94 b, becomes a low-pressure refrigerant, and is guided to evaporator 93.

The liquid refrigerant sent to evaporator 93 is evaporated by heat exchange and is discharged as the gas refrigerant or the gas refrigerant partially mixed with the liquid refrigerant. The refrigerant discharged from evaporator 93 is incorporated in the compression chamber of compressor 91.

Meanwhile, the gas refrigerant separated by gas-liquid separator 96 and being at an intermediate pressure passes through injection pipe 95 and is guided to the compression chamber in compressor 91. Although not illustrated, a closure valve or an expansion valve may be provided in injection pipe 95 and may be configured to adjust and stop the injection pressure.

Compressor 91 compresses a low-pressure refrigerant flowing from evaporator 93, injects the refrigerant in gas-liquid separator 96 at an intermediate pressure to the compression chamber in a compression process to compress the refrigerant, and sends the high-temperature high-pressure refrigerant from a discharge tube to condenser 92.

In a ratio of the liquid-phase component to the gas-phase component separated by gas-liquid separator 96, as a pressure difference between an inlet-side pressure and an outlet-side pressure of expansion valve 94 a provided on the upstream side increases, the amount of the gas-phase component increases. Further, as a supercooling degree of the refrigerant at an outlet of condenser 92 decreases or a depletion degree thereof increases, the amount of the gas-phase component increases.

Meanwhile, the amount of the refrigerant sucked through injection pipe 95 by compressor 91 increases as the intermediate pressure increases. Thus, when the refrigerant of which the ratio of the gas-phase component is more than the ratio of the gas-phase component of the refrigerant separated by gas-liquid separator 96 is sucked from injection pipe 95, the gas refrigerant in gas-liquid separator 96 is depleted, and the liquid refrigerant flows to injection pipe 95. It is preferable that in order to maximize capacity of compressor 91, the gas refrigerant separated by gas-liquid separator 96 is sucked from injection pipe 95 to compressor 91. However, when the refrigerant escapes from this balanced state, the liquid refrigerant flows from injection pipe 95 to compressor 91. Thus, even in this case, it is necessary that compressor 91 is configured to maintain high reliability.

FIG. 2 is a longitudinal sectional view showing the scroll compressor according to the present embodiment. FIG. 3 is an enlarged view showing a main part of FIG. 2. FIG. 4 is a view taken along line 4-4 of FIG. 3. FIG. 5 is a view taken along line 4-4 of FIG. 4.

As illustrated in FIG. 2, compressor 91 includes compression mechanism 2, motor unit 3, and oil reservoir 20 inside sealed container 1.

Compression mechanism 2 includes main bearing member 11 fixed to sealed container 1 through welding or shrink fitting, fixed scroll (a compression chamber partitioning member) 12 fixed to main bearing member 11 through a bolt, and orbiting scroll 13 engaged with fixed scroll 12. Shaft 4 is pivotally supported by main bearing member 11.

Rotation restraining mechanism 14 such as an Oldham ring, which prevents rotation of orbiting scroll 13 and guides orbiting scroll 13 to perform a circular orbiting movement, is provided between orbiting scroll 13 and main bearing member 11.

Orbiting scroll 13 is eccentrically driven by eccentric shaft portion 4 a at an upper end of shaft 4 and circularly orbits by rotation restraining mechanism 14.

Compression chamber 15 is formed between fixed scroll 12 and orbiting scroll 13.

Suction pipe 16 penetrates sealed container 1 to the outside, and suction port 17 is provided at an outer circumferential portion of fixed scroll 12. The working fluid (the refrigerant) sucked from suction pipe 16 is guided from suction port 17 to compression chamber 15. Compression chamber 15 moves from an outer circumferential side to a central portion while the volume thereof is reduced. The working fluid that reaches a predetermined pressure in compression chamber 15 is discharged from discharge port 18 provided at a central portion of fixed scroll 12 to discharge chamber 31. Discharge reed valve 19 is provided in discharge port 18. The working fluid that reaches the predetermined pressure in compression chamber 15 pushes and opens discharge reed valve 19 to be discharged to discharge chamber 31. The working fluid discharged to discharge chamber 31 is discharged to the outside of sealed container 1.

Meanwhile, the working fluid at the intermediate pressure, guided from injection pipe 95, flows to intermediate pressure chamber 41, opens check valve 42 provided in injection port 43, is injected into compression chamber 15 after working fluid is enclosed, and is discharged from discharge port 18 into sealed container 1 together with the working fluid sucked from suction port 17.

Pump 25 is provided at a lower end of shaft 4. Pump 25 is disposed such that a suction port thereof exists in oil reservoir 20.

Pump 25 is driven by shaft 4 and can certainly pump up oil 6 in oil reservoir 20 provided at a bottom portion of sealed container 1 regardless of a pressure condition and an operation speed. Thus, a concern about shortage of oil 6 is alleviated. Oil 6 pumped up by pump 25 is supplied to compression mechanism 2 through oil supplying hole 26 formed in shaft 4. Before and after oil 6 is pumped up by pump 25, when foreign substances are removed from oil 6 by an oil filter or the like, the foreign substances can be prevented from being introduced into compression mechanism 2, and reliability can be further improved.

The pressure of oil 6 guided to compression mechanism 2 is substantially the same as a discharge pressure of the scroll compressor and serves as a back pressure source for orbiting scroll 13. Accordingly, orbiting scroll 13 stably exhibits a predetermined compression function without being separated from or colliding with fixed scroll 12.

As illustrated in FIG. 3, ring-shaped sealing member 78 is disposed on rear surface 13 e of an end plate of orbiting scroll 13.

High-pressure area 30 is formed inside sealing member 78, and back-pressure chamber 29 is formed outside sealing member 78. Back-pressure chamber 29 is set to a pressure between a high pressure and a low pressure. Since high-pressure area 30 and back-pressure chamber 29 can be separated from each other using sealing member 78, application of the pressure from rear surface 13 e of orbiting scroll 13 can be stably controlled.

As shown in FIG. 6 which is a view taken along line 6-6 of FIG. 3, compression chamber 15 having fixed scroll 12 and orbiting scroll 13 includes first compression chamber 15 a formed on an outer wall side of a wrap of orbiting scroll 13 and second compression chamber 15 b formed on an inner wall side of the wrap.

Connection passage 55 from high-pressure area 30 to back-pressure chamber 29 and supply passage 56 from back-pressure chamber 29 to second compression chamber 15 b are provided as an oil supplying passage from oil reservoir 20 illustrated in FIG. 3. As connection passage 55 from high-pressure area 30 to back-pressure chamber 29 is provided, oil 6 can be supplied to a sliding portion of rotation restraining mechanism 14 and a thrust sliding portion of fixed scroll 12 and orbiting scroll 13.

One first opening end 55 a of connection passage 55 is formed on rear surface 13 e of orbiting scroll 13 and travels between the inside and the outside of sealing member 78, and the other second opening end 55 b is always open to high-pressure area 30.

Accordingly, intermittent oil supplying can be realized.

A part of oil 6 enters a fitting portion between eccentric shaft portion 4 a and orbiting scroll 13 and bearing portion 66 between shaft 4 and main bearing member 11 so as to obtain an escape area by supply pressure or self weight, falls after lubricating each component, and returns to oil reservoir 20.

In the scroll compressor according to the present embodiment, the oil supplying passage to compression chamber 15 is configured with passage 13 a formed inside orbiting scroll 13 and recess 12 a formed in a wrap side end plate of fixed scroll 12. Third opening end 56 a of passage 13 a is formed at wrap tip end 13 c and is periodically opened to recess 12 a according to the orbiting movement. Further, fourth opening end 56 b of passage 13 a is always open to back-pressure chamber 29. Accordingly, back-pressure chamber 29 and second compression chamber 15 b can intermittently communicate with each other.

Injection port 43 for injecting the refrigerant at the intermediate pressure is provided to penetrate the end plate of fixed scroll 12. Injection port 43 is sequentially open to first compression chamber 15 a and second compression chamber 15 b. Injection port 43 is provided at a position where injection port 43 is open during a compression process after the refrigerant is introduced into and closed in first compression chamber 15 a and second compression chamber 15 b.

Discharge bypass port 21 through which the refrigerant compressed in compression chamber 15 is discharged before discharge bypass port 21 communicates with discharge port 18 is provided in the end plate of fixed scroll 12.

As illustrated in FIGS. 3 and 4, compressor 91 according to the present embodiment is provided with intermediate pressure chamber 41 that guides an intermediate pressure working fluid fed from injection pipe 95 and before being injected into compression chamber 15.

Intermediate pressure chamber 41 is formed with fixed scroll 12 that is a compression chamber partitioning member, intermediate pressure plate 44, and intermediate pressure cover 45. Intermediate pressure chamber 41 and compression chamber 15 face each other with fixed scroll 12 interposed therebetween. Intermediate pressure chamber 41 has intermediate pressure chamber inlet 41 a into which the intermediate pressure working fluid flows and liquid reservoir 41 b formed at a position lower than intermediate pressure chamber inlet 41 a and injection port inlet 43 a of injection port 43 through which the intermediate pressure working fluid is injected into compression chamber 15.

Liquid reservoir 41 b is formed on an upper surface of the end plate of fixed scroll 12.

Intermediate pressure plate 44 is provided with check valve 42 that prevents backflow of the refrigerant from compression chamber 15 to intermediate pressure chamber 41. In a section in which injection port 43 is open to compression chamber 15, when the internal pressure of compression chamber 15 is higher than the intermediate pressure of injection port 43, the refrigerant flows backward from compression chamber 15 to intermediate pressure chamber 41. Thus, check valve 42 is provided to prevent the backflow of the refrigerant.

In compressor 91 according to the present embodiment, check valve 42 is configured with reed valve 42 a lifted to compression chamber 15 side and causing compression chamber 15 and intermediate pressure chamber 41 to communicate with each other. Check valve 42 causes compression chamber 15 and intermediate pressure chamber 41 to communicate with each other only when the internal pressure of compression chamber 15 is lower than the pressure of intermediate pressure chamber 41. By using reed valve 42 a, the number of sliding portions in a movable portion becomes small, sealing performance can be maintained for a long time, and a flow passage area can be easily enlarged as needed. When check valve 42 is not provided or check valve 42 is provided in injection pipe 95, the refrigerant in compression chamber 15 flows backward to injection pipe 95, and unnecessary compression power is consumed. Check valve 42 according to the present embodiment is provided in intermediate pressure plate 44 close to compression chamber 15 to suppress the backflow from compression chamber 15.

The upper surface of the end plate of fixed scroll 12 is located closer to intermediate pressure chamber inlet 41 a, and the upper surface of the end plate of fixed scroll 12 is provided with liquid reservoir 41 b in which the working fluid in a liquid-phase component is collected. Further, injection port inlet 43 a is provided at a position higher than the height of intermediate pressure chamber inlet 41 a. Thus, among the intermediate pressure working fluid, the working fluid in a gas-phase component is guided to injection port 43. Since the working fluid in the liquid-phase component collected in liquid reservoir 41 b is evaporated in the surface of fixed scroll 12 in a high-temperature state, it is difficult for the working fluid in the liquid-phase component to flow into compression chamber 15.

Further, intermediate pressure chamber 41 and discharge chamber 31 are provided adjacent to each other through intermediate pressure plate 44. It is possible to suppress an increase in the temperature of the high-pressure refrigerant of discharge chamber 31 while evaporation when the working fluid in the liquid-phase component flows into intermediate pressure chamber 41 is promoted. Thus, operation can be performed even in a high discharge pressure condition by that degree.

The intermediate pressure working fluid guided to injection port 43 pushes and opens reed valve 42 a by a pressure difference between injection port 43 and compression chamber 15 and is joined to a low-pressure working fluid sucked by suction port 17 in compression chamber 15. However, the intermediate pressure working fluid remaining in injection port 43 between check valve 42 and compression chamber 15 is repeatedly expanded and compressed again, which causes a decrease in efficiency of compressor 91.

Thus, the thickness of valve stop 42 b (see FIG. 5) for regulating a maximum displacement of reed valve 42 a is changed according to the lift regulation point of reed valve 42 a, and the volume of injection port 43 downstream of reed valve 42 a is small.

Further, reed valve 42 a and valve stop 42 b illustrated in FIG. 5 are fixed to intermediate pressure plate 44 through fixing member 46 having a bolt. A fixing hole of fixing member 46 provided in valve stop 42 b is opened only to the insertion side of fixing member 46 without penetrating valve stop 42 b. As a result, fixing member 46 is configured to be open only in intermediate pressure chamber 41.

Accordingly, leakage of the working fluid between intermediate pressure chamber 41 and compression chamber 15 through a gap of fixing member 46 can be suppressed, so that the injection rate can be improved.

Intermediate pressure chamber 41 illustrated in FIG. 3 has a suction volume that is equal to or more than a suction volume of compression chamber 15 to be able to perform sufficient supplying to compression chamber 15 by an injection amount. Herein, the suction volume is the volume of compression chamber 15 at a time point when the working fluid guided from suction port 17 is introduced into and closed in compression chamber 15, that is, at a time point when a suction process is completed, and is the total volume of first compression chamber 15 a and second compression chamber 15 b. In compressor 91 according to the present embodiment, intermediate pressure chamber 41 is provided to be spread on a flat surface of the end plate of fixed scroll 12 so as to expand the volume thereof. However, when a part of oil 6 enclosed in compressor 91 goes out from compressor 91 together with a discharge refrigerant, and returns to intermediate pressure chamber 41 through injection pipe 95 from gas-liquid separator 96, if the amount of oil 6 remaining in liquid reservoir 41 b is too large, oil 6 in oil reservoir 20 runs short. Thus, it is not appropriate that the volume of intermediate pressure chamber 41 is too large. Because of this, it is preferable that the volume of intermediate pressure chamber 41 is equal to or more than the suction volume of compression chamber 15, and is equal to or less than a half of the oil volume of enclosed oil 6.

FIG. 6 is a view taken along line 6-6 of FIG. 3.

FIG. 6 is a view showing a state in which orbiting scroll 13 is engaged with fixed scroll 12 when viewed from rear surface 13 e side of orbiting scroll 13. As illustrated in FIG. 6, in a state in which fixed scroll 12 and orbiting scroll 13 are engaged with each other, the number of winding of the spiral wrap of fixed scroll 12 is equal to the number of winding of the spiral wrap of orbiting scroll 13.

Compression chamber 15 formed with fixed scroll 12 and orbiting scroll 13 includes first compression chamber 15 a formed on an outer wall side of the wrap of orbiting scroll 13 and second compression chamber 15 b formed on an inner wall side of the wrap of orbiting scroll 13.

A timing when the working fluid is confined in first compression chamber 15 a is substantially the same as a timing when the working fluid is confined in second compression chamber 15 b, and compression of first compression chamber 15 a and second compression chamber 15 b simultaneously starts. Accordingly, a pressure balance between first compression chamber 15 a and second compression chamber 15 b is maintained, and behavior of orbiting scroll 13 is stabilized.

In FIG. 7, R is a pressure curve showing the internal pressure of the compression chamber of the scroll compressor when an injection operation is not accompanied.

When the injection operation is not accompanied, pressure increasing rates of first compression chamber 15 a and second compression chamber 15 b according to a crank rotation angle are equal to each other. However, when the amounts of the injection to first compression chamber 15 a and second compression chamber 15 b differ from each other, the pressure increasing rates according to the amounts of the injection differ from each other.

FIG. 7 shows a difference in a compression rate due to a difference in the amount of the injection. The compression chamber where the amount of the injection is large reaches a discharge pressure in a short compression section from start of compression. In the present embodiment, since the amount of the refrigerant injected into first compression chamber 15 a increases, the pressure increasing rate of first compression chamber 15 a as indicated by pressure curve P is faster than the pressure increasing rate of second compression chamber 15 b as indicated by pressure curve Q. In FIG. 7, when discharge bypass port 21 is provided according to the internal pressure of the compression chamber having a small injection amount indicated by pressure curve Q, the internal pressure of the compression chamber having a large amount of the injection indicated by pressure curve P reaches the discharge pressure faster than the internal pressure indicated by pressure curve Q. However, even after the pressure reaches the discharge pressure, first compression chamber 15 a that has been continuously compressed without an escape area is excessively compressed. After first compression chamber 15 a communicates with discharge bypass port 21, the excessive compression is alleviated. That is, an additional compression power corresponding to area A in the drawing is required. Thus, in the present invention, discharge bypass port 21 is provided at a position where first compression chamber 15 a having a large amount of the injection can perform the discharge at an earlier timing than second compression chamber 15 b.

That is, the internal pressure of the compression chamber having a large amount of the injection increases due to the injection refrigerant, and the pressure of the compression chamber having a low injection amount or without the injection increases slower than the other compression chamber. In other words, the compression chamber having a large amount of the injection is required to be brought in a dischargeable state at an earlier timing than the other compression chamber. However, in the symmetric scroll compression in which the amounts of the injection are necessarily different from each other, when the injection operation is performed without considering this fact, efficiency deteriorates. In the present embodiment, discharge bypass port 21 is provided at a position where first compression chamber 15 a having a large amount of injection can perform discharge at an earlier timing than second compression chamber 15 b. As a result, a volume ratio is defined by a ratio of a suction volume of the compression chamber to a volume of the compression chamber which communicates with the discharge port and discharge bypass port 21. A volume ratio of first compression chamber 15 a having a large injection amount is equal to or less than that of second compression chamber 15 b.

As shown in FIG. 7, an opening section of injection port 43 to second compression chamber 15 b overlaps with at least a partial section of an oil supplying section from back-pressure chamber 29 to second compression chamber 15 b. An overlapping section in which the oil supplying section overlaps with the opening section is a partial section of the second half of the oil supplying section. Injection port 43 is open to the second half of the oil supplying section, so that the opening section starts.

Further, a slope shape is provided at wrap tip end 13 c of orbiting scroll 13 from a winding start portion that is a central portion to a winding end portion that is an outer circumferential portion based on a result obtained by measuring a temperature distribution during operation such that a wing height gradually increases. Accordingly, a dimensional change due to heat expansion is absorbed, and local sliding is easily prevented.

FIG. 8 is a diagram for illustrating a positional relationship between an oil supplying passage and a sealing member accompanying an orbiting movement of the scroll compressor according to the present embodiment.

FIG. 8 is a view illustrating a state in which orbiting scroll 13 is engaged with fixed scroll 12 when viewed from rear surface 13 e side of orbiting scroll 13, in which the phases of orbiting scroll 13 are sequentially shifted by 90 degrees.

First opening end 55 a of connection passage 55 is formed on rear surface 13 e of orbiting scroll 13.

As illustrated in FIG. 8, rear surface 13 e of orbiting scroll 13 is partitioned into high-pressure area 30 on an inner side and back-pressure chamber 29 on an outer side by sealing member 78.

In a state of FIG. 8(B), since first opening end 55 a is open to back-pressure chamber 29 that is an outer side of sealing member 78, oil 6 is supplied.

In contrast, in FIGS. 8(A), 8(C), and 8(D), since first opening end 55 a is open to an inside of sealing member 78, oil is not supplied.

That is, although first opening end 55 a of connection passage 55 travels between high-pressure area 30 and back-pressure chamber 29, oil 6 is supplied to back-pressure chamber 29 only when a pressure difference occurs between first opening end 55 a and second opening end 55 b of connection passage 55. With this configuration, since the amount of the supplied oil can be adjusted at a rate of time when first opening end 55 a travels between the inside and the outside of sealing member 78, the passage diameter of connection passage 55 can be configured to be 10 times or more the size of the oil filter. Accordingly, since there is no risk that foreign substances are caught by passage 13 a and passage 13 a is blocked, the scroll compressor can be provided in which the back pressure can be stably applied and lubrication of the thrust sliding portion, rotation restraining mechanism 14 can be maintained in a good state, and high efficiency and high reliability can be realized. In the present embodiment, a case where second opening end 55 b is always located in high-pressure area 30 and first opening end 55 a travels between high-pressure area 30 and back-pressure chamber 29 has been described as an example. However, even when second opening end 55 b travels between high-pressure area 30 and back-pressure chamber 29, and first opening end 55 a is always located in back-pressure chamber 29, a pressure difference occurs between first opening end 55 a and second opening end 55 b. Thus, intermittent oil supplying can be realized and similar effects can be obtained.

FIG. 9 is a diagram for illustrating an opening state of the oil supplying passage and an injection port accompanying the orbiting movement of the scroll compressor according to the present embodiment.

FIG. 9 shows a state in which orbiting scroll 13 is engaged with fixed scroll 12, in which the phases of fixed scroll 12 are sequentially shifted by 90 degrees.

As illustrated in FIG. 9, intermittent communication is realized by periodically opening third opening end 56 a of passage 13 a formed in wrap tip end 13 c to recess 12 a formed in the end plate of fixed scroll 12.

In a state of FIG. 9(D), third opening end 56 a is open to recess 12 a. In this state, oil 6 is supplied from back-pressure chamber 29 to second compression chamber 15 b through supply passage 56 or passage 13 a. In this way, the oil supplying passage by third opening end 56 a is provided at a position that is open to second compression chamber 15 b during a compression stroke after the suction refrigerant is introduced and closed.

In contrast, in FIGS. 9(A), 9(B), and 9(C), since third opening end 56 a is not open to recess 12 a, oil 6 is not supplied from back-pressure chamber 29 to second compression chamber 15 b. Hereinabove, since oil 6 in back-pressure chamber 29 is intermittently guided to second compression chamber 15 b through the oil supplying passage, a fluctuation in the pressure of back-pressure chamber 29 can be suppressed, and control can be performed to a predetermined pressure. Further, similarly, oil 6 supplied to second compression chamber 15 b serves to improve the sealing property and the lubricity during the compression.

In FIG. 9(C) showing a time point when first compression chamber 15 a is closed, injection port 43 is open to first compression chamber 15 a.

On the other hand, in a state of FIG. 9(A) showing a state in which the compression is progressed, injection port 43 is open to second compression chamber 15 b. Accordingly, even though the opening section of injection port 43 is substantially the same as a section between first compression chamber 15 a and second compression chamber 15 b, a larger amount of the injection refrigerant is sent to first compression chamber 15 a that performs injection to the compression chamber having a low pressure immediately after the compression starts, and an increase in the pressure of first compression chamber 15 a is quickened with respect to second compression chamber 15 b. Further, in any compression chamber, since the injection refrigerant can be compressed without flowing back to suction port 17, it is easy to increase the amount of a circulating refrigerant and it is possible to perform a highly efficient injection operation.

In this way, injection port 43 is provided at a position where injection port 43 is sequentially open to first compression chamber 15 a and second compression chamber 15 b. Further, injection port 43 is provided to penetrate the end plate of fixed scroll 12 at a position where injection port 43 is open to first compression chamber 15 a during the compression stroke after the suction refrigerant is introduced and closed as illustrated in FIGS. 9(C) and 9(D) or at a position where injection port 43 is open to second compression chamber 15 b during the compression stroke after the suction refrigerant is introduced and closed as illustrated in FIG. 9(A) and FIG. 9(B).

In FIG. 9, the oil supplying section starts from FIG. 9(C) to FIG. 9(D). Injection port 43 is later open to second compression chamber 15 b between FIG. 9(A) and FIG. 9(B), and the opening section of injection port 43 has an overlapping section between the opening section and the oil supplying section. In the present embodiment, the oil supplying section is the same as an opening of third opening end 56 a to recess 12 a. The pressure of back-pressure chamber 29 depends on the internal pressure of compression chamber 15 at an end of the oil supplying section, and the injection refrigerant is sent to compression chamber 15 from a middle of the oil supplying section. Thus, the pressure of back-pressure chamber 29 increases only during the injection operation, and it is possible to suppress destabilization of the behavior of orbiting scroll 13. Further, the reason why start of the opening of injection port 43 to compression chamber 15 is not hastened until the first half of the oil supplying section is as follows. That is, when the internal pressure of compression chamber 15 increases due to the injection refrigerant from an early stage of the oil supplying section, the internal pressure of compression chamber 15 and the pressure of back-pressure chamber 29 become equal to each other before the oil is sufficiently supplied to compression chamber 15 from back-pressure chamber 29. Thus, a possibility that a problem occurs in reliability of compressor that lacks oil supplying increases.

At least a part of the oil supplying section to compression chamber 15 is configured to overlap with an opening section of injection port 43. Thus, application of the pressure from rear surface 13 e to orbiting scroll 13 increases together with the internal pressure of compression chamber 15 during the oil supplying section as the intermediate pressure of the injection refrigerant increases. Therefore, orbiting scroll 13 is more stably pressed against fixed scroll 12, so that stable operation can be performed while leakage from back-pressure chamber 29 to compression chamber 15 is reduced. Accordingly, the behavior of orbiting scroll 13 can more stably realize optimum performance, and can further improve an injection rate.

In FIG. 9, at a central portion of the end plate of fixed scroll 12, discharge port 18 through which the refrigerant compressed in the compression chamber is discharged is provided, and discharge bypass port 21 a provided at a position communicating with first compression chamber 15 a and discharge bypass port 21 b provided at a position communicating with second compression chamber 15 b are provided as discharge bypass port 21.

First compression chamber 15 a closes the suction refrigerant in a state of FIG. 9(C), and discharge bypass port 21 a is open to first compression chamber 15 a in a state of FIG. 9(D).

On the other hand, although second compression chamber 15 b closes the suction refrigerant in a state of FIG. 9(C), discharge bypass port 21 b does not yet communicate with second compression chamber 15 b in the states of FIG. 9(D) and FIG. 9(A) and communicates with second compression chamber 15 b in a state of FIG. 9(B).

Accordingly, even when first compression chamber 15 a receives a larger amount of the injection refrigerant than that of second compression chamber 15 b, first compression chamber 15 a is not over-compressed, and an effect of the injection cycle can be exhibited.

In this way, even when discharge bypass port 21 a communicating with first compression chamber 15 a and discharge bypass port 21 b communicating with second compression chamber 15 b are provided, a volume ratio, which is a ratio of the suction volume to the discharge volume of compression chamber 15 at which the refrigerant in compression chamber 15 can be discharged, can be smaller in first compression chamber 15 a than in second compression chamber 15 b.

Therefore, even in a maximum injection state, an excessive increase in the pressure of first compression chamber 15 a can be suppressed.

Second Embodiment

FIG. 10 is a longitudinal sectional view showing a scroll compressor according to a second embodiment of the present invention.

In the present embodiment, first injection port 48 a that is open only to first compression chamber 15 a and second injection port 48 b that is open only to second compression chamber 15 b are included. First injection port 48 a is provided with first check valve 47 a, and second injection port 48 b is provided with second check valve 47 b. Since the other configuration is the same as the configuration of the embodiment, the same reference numerals are designated, and description thereof will be omitted.

In the present embodiment, as the port diameter of first injection port 48 a is more than the port diameter of second injection port 48 b, the amount of the refrigerant injected from first injection port 48 a into first compression chamber 15 a is more than the amount of the refrigerant injected from second injection port 48 b into second compression chamber 15 b.

In this way, as first injection port 48 a that is open only to first compression chamber 15 a and second injection port 48 b that is open only to second compression chamber 15 b are provided, the amounts of the injection to first compression chamber 15 a and second compression chamber 15 b can be individually adjusted. In addition, the refrigerant can be always injected into first compression chamber 15 a and second compression chamber 15 b or can be simultaneously injected into first compression chamber 15 a and second compression chamber 15 b. Thus, it is effective to achieve a high injection rate under a condition in which a pressure difference in the refrigeration cycle is large. Further, since the degree of freedom in setting the oil supplying section from back-pressure chamber 29 increases, a pressure adjusting function can be effectively utilized in back-pressure chamber 29, and addition of the pressure from rear surface 13 e of orbiting scroll 13 can be stably controlled.

In the present embodiment, a case where first injection port 48 a has a larger port diameter than second injection port 48 b has been shown. However, with this configuration or instead of this configuration, the opening section in which first injection port 48 a is open to first compression chamber 15 a may be longer than the opening section in which second injection port 48 b is open to second compression chamber 15 b. Further, a pressure difference between the intermediate pressure in first injection port 48 a and the internal pressure of first compression chamber 15 a when first injection port 48 a is open to first compression chamber 15 a may be more than a pressure difference between the intermediate pressure in second injection port 48 b and the internal pressure of second compression chamber 15 b when second injection port 48 b is open to second compression chamber 15 b.

Further, in the present embodiment, first injection port 48 a and second injection port 48 b respectively open only to first compression chamber 15 a and second compression chamber 15 b have been described. However, using an injection port open to both first compression chamber 15 a and second compression chamber 15 b shown in the first embodiment or a combination of first injection port 48 a and second injection port 48 b respectively open only to first compression chamber 15 a and second compression chamber 15 b shown in the present embodiment, the amount of the injection into first compression chamber 15 a may be more than the amount of the injection into second compression chamber 15 b.

When R32 or carbon dioxide, in which the temperature of a discharged refrigerant is easy to be high, is used as a refrigerant that is a working fluid, an effect of suppressing an increase in the temperature of the discharged refrigerant is exhibited. Thus, deterioration of a resin material such as an insulating material of motor unit 3 (see FIG. 2) can be suppressed, and a compressor that is reliable for a long time can be provided.

Meanwhile, when a refrigerant having a double bond between carbons or a refrigerant including the refrigerant and having a global warming potential (GWP; a global warming factor) of 500 or less is used, a refrigerant decomposition reaction is likely to occur at high temperatures. Thus, an effect for long-term stability of the refrigerant is exhibited according to the effect of suppressing the increase in the temperature of the discharge refrigerant.

As described above, in the scroll compressor according to the first disclosure, at the central portion of the first end plate of the fixed scroll, the discharge port through which the refrigerant compressed in the compression chamber is discharged is included, and the discharge bypass port through which the refrigerant compressed in the compression chamber is discharged before the compression chamber communicates with the discharge port is provided.

Further, at least one injection port through which an intermediate-pressure refrigerant is injected into the first compression chamber or the second compression chamber is provided to penetrate the end plate of the fixed scroll at a position where the injection port is open to the first compression chamber or the second compression chamber during the compression stroke after the suction refrigerant is introduced and closed. Further, the discharge bypass port is disposed such that a volume ratio is made smaller in one compression chamber among the first compression chamber and the second compression chamber, which has the large amount of the refrigerant injected from the injection port than in the other compression chamber, the volume ratio being a ratio of the suction volume to the discharge volume of the compression chamber at which the refrigerant in the compression chamber can be discharged.

According to the present disclosure, in the scroll compressor in which the discharge volume and the suction volume are equal to each other in the first compression chamber and the second compression chamber, the volume ratios of the first compression chamber and the second compression chamber are also equal to each other. However, as more injection to one compression chamber is performed, the internal pressure of the compression chamber reaches the discharge pressure in a shorter compression section of compression chamber than that of the other compression chamber. Even when the internal pressure of the compression chamber reaches the discharge pressure, if the dischargeable port and the compression chamber do not communicate with each other, excessive compression occurs. Not only an extra compression power is required, but also a force for separating the orbiting scroll from the fixed scroll is generated. Thus, compression motion deteriorates. The discharge bypass port is disposed such that the volume ratio is smaller in the one compression chamber having the large amount of the injected refrigerant than in the other compression chamber. Thus, even in a maximum injection state, an excessive increase in the pressure can be suppressed. That is, according to the present embodiment, the discharge bypass port early communicates with the compression chamber having the large amount of the injection, and the volume ratio is reduced. Thus, excessive compression can be prevented even during operation at a high injection rate, the injection cycle effect can be maximized, and efficiency improvement and capacity expansion effect can be obtained more than the related art.

According to a second disclosure, in the scroll compressor according to the first disclosure, the injection port is provided with a check valve which allows flow of the refrigerant to the compression chamber and suppresses flow of the refrigerant from the compression chamber.

According to the present disclosure, as the check valve and the compression chamber are provided close to each other, even when the internal pressure of the compression chamber increases to the intermediate pressure or more in a section in which the injection port is open to the compression chamber, the compression of the refrigerant in a space that is ineffective for compression, such as the injection pipe can be minimized, and the injection rate can be increased to a condition in which theoretical performance of the injection cycle can be exhibited to maximum.

According to a third disclosure, in the scroll compressor according to the first disclosure or the second disclosure, the oil reservoir in which the oil is stored is formed in the sealed container including the fixed scroll and the orbiting scroll therein, and the high-pressure area and the back-pressure chamber are formed on the rear surface of the orbiting scroll.

Further, the oil supplying passage through which the oil is supplied from the oil reservoir to the compression chamber passes through the back-pressure chamber, and the oil supplying passage through which the back-pressure chamber communicates with the first compression chamber and the second compression chamber is provided at a position open to the first compression chamber or the second compression chamber during the compression stroke after the suction refrigerant is introduced and closed.

Further, at least a partial section of the oil supplying section in which the oil supplying passage communicates with the first compression chamber or the second compression chamber overlaps with the opening section in which the injection port is open to the first compression chamber or the second compression chamber.

When the intermediate-pressure refrigerant is injected into the compression chamber, the pressure of the compression chamber more quickly increases than in a case where the intermediate-pressure refrigerant is not injected. Thus, a force for separating the orbiting scroll from the fixed scroll increases more than in the related art. According to the present disclosure, a force for pressing the orbiting scroll against the fixed scroll interlocks with the pressure of the compression chamber with which the oil supplying passage communicates. Therefore, as the intermediate-pressure refrigerant is injected into the compression chamber, the force for pressing the orbiting scroll against the fixed scroll increases, and stable operation can be performed while the orbiting scroll is not separated from the fixed scroll.

According to a fourth disclosure, in the scroll compressor according to the third disclosure, the overlapping section where the oil supplying section overlaps with the opening section is a part of the latter half of the oil supplying section.

According to the present disclosure, since the pressure of the back-pressure chamber interlocks with the internal pressure of the compression chamber in the second half of the overlapping section, the pressure of the back-pressure chamber can be set according to the internal pressure of the compression chamber in a state in which the injection is completed or in a state in which the injection is further performed.

Accordingly, under a condition in which a separation force of the orbiting scroll by the injection is large, the pressure of the back-pressure chamber is high and stable orbiting movement is possible. On the other hand, under a condition in which the injection amount is small, the pressure of the back-pressure chamber is low, and an excessive pressing force against the fixed scroll can be prevented.

According to a fifth disclosure, in the scroll compressor according to any one embodiment of the first disclosure to the fourth disclosure, at least one injection port is provided at a position where the injection port is sequentially open to the first compression chamber and the second compression chamber.

According to the present disclosure, since the injection port can be shared when the injection into both the first and second compression chambers is performed, miniaturization and a reduction in the number of components can be achieved, and the injection rate increases so that the injection cycle effect can be maximized. Further, in general, in the scroll compressor, compression start timings of the first compression chamber and the second compression chamber are different from each other by 180 degrees. Thus, immediately after start of the compression from one injection port even to any compression chamber, the injection port may be provided at a position where the injection is performed, and is suitable for realizing a high injection rate.

According to a sixth disclosure, in the scroll compressor according to any one embodiment of the first disclosure to the fourth disclosure, the injection port includes the first injection port that is open only to the first compression chamber and the second injection port that is open only to the second compression chamber. Further, one of the following configurations (1) to (3) is added.

(1) Further, the first injection port has a larger port diameter than the second injection port. (2) The opening section in which the first injection port is open to the first compression chamber is longer than the opening section in which the second injection port is open to the second compression chamber. (3) the pressure difference between the intermediate pressure in the first injection port and the internal pressure of the first compression chamber when the first injection port is open to the first compression chamber is more than the pressure difference between the intermediate pressure of the second injection port and the internal pressure of the second compression chamber when the second injection port is open to the second compression chamber.

According to the present disclosure, the amount of injection into the first compression chamber having a large volume and a slow pressure increase rate can be certainly increased, and efficient distribution of the amount of the injected refrigerant can be achieved.

INDUSTRIAL APPLICABILITY

The scroll compressor is useful for a refrigeration cycle apparatus, such as a hot water heater, an air conditioner, a water heater, and a refrigerator, in which an evaporator is used in a low temperature environment.

REFERENCE MARKS IN THE DRAWINGS

-   -   1 SEALED CONTAINER     -   2 COMPRESSION MECHANISM     -   3 MOTOR UNIT     -   4 SHAFT     -   4 a ECCENTRIC SHAFT PORTION     -   6 OIL     -   11 MAIN BEARING MEMBER     -   12 FIXED SCROLL     -   12 a RECESS     -   13 ORBITING SCROLL     -   13 c WRAP TIP END     -   13 e REAR SURFACE     -   14 ROTATION RESTRAINING MECHANISM     -   15 COMPRESSION CHAMBER     -   15 a FIRST COMPRESSION CHAMBER     -   15 b SECOND COMPRESSION CHAMBER     -   16 SUCTION PIPE     -   17 SUCTION PORT     -   18 DISCHARGE PORT     -   19 DISCHARGE REED VALVE     -   20 OIL RESERVOIR     -   21, 21 a, 21 b DISCHARGE BYPASS PORT     -   25 PUMP     -   26 OIL SUPPLYING HOLE     -   29 BACK-PRESSURE CHAMBER     -   30 HIGH-PRESSURE AREA     -   31 DISCHARGE CHAMBER     -   41 INTERMEDIATE-PRESSURE CHAMBER     -   41 a INTERMEDIATE-PRESSURE CHAMBER INLET     -   41 b LIQUID RESERVOIR     -   42 CHECK VALVE     -   42 a REED VALVE     -   42 b VALVE STOP     -   43 INJECTION PORT     -   43 a INJECTION PORT INLET     -   44 INTERMEDIATE-PRESSURE PLATE (INTERMEDIATE PRESSURE CHAMBER         PARTITION MEMBER)     -   45 INTERMEDIATE-PRESSURE COVER (INTERMEDIATE PRESSURE CHAMBER         PARTITION MEMBER)     -   46 FIXING MEMBER     -   47 a FIRST CHECK VALVE     -   47 b SECOND CHECK VALVE     -   48 INJECTION PORT     -   48 a FIRST INJECTION PORT     -   48 b SECOND INJECTION PORT     -   55 CONNECTION PASSAGE     -   55 a FIRST OPENING END     -   55 b SECOND OPENING END     -   56 SUPPLY PASSAGE     -   56 a THIRD OPENING END     -   56 b FOURTH OPENING END     -   66 BEARING PORTION     -   78 SEALING MEMBER     -   91 COMPRESSOR     -   92 CONDENSER     -   93 EVAPORATOR     -   94 a, 94 b EXPANSION VALVES     -   95 INJECTION PIPE     -   96 GAS-LIQUID SEPARATOR 

1. A scroll compressor comprising: a fixed scroll including a first spiral wrap standing up from a first end plate of the fixed scroll; and an orbiting scroll including a second spiral wrap standing up from a second end plate of the orbiting scroll, wherein the first spiral wrap of the fixed scroll is engaged with the second spiral wrap of the orbiting scroll to define a compression chamber between the fixed scroll and the orbiting scroll, the compression chamber includes: a first compression chamber on an outer wall side of the second spiral wrap of the orbiting scroll; and a second compression chamber on an inner wall side of the second spiral wrap of the orbiting scroll, a suction volume of the first compression chamber is equal to a suction volume of the second compression chamber, wherein the first end plate of the fixed scroll includes a central portion having a discharge port through which a refrigerant compressed in the compression chamber is discharged, the scroll compressor further comprises: a discharge bypass port through which the refrigerant compressed in the compression chamber is discharged before the compression chamber communicates with the discharge port is provided; at least one injection port through which an intermediate-pressure refrigerant is injected into the first compression chamber and the second compression chamber, the at least one injection port penetrating the first end plate of the fixed scroll at a position where the injection port is open to the first compression chamber or the second compression chamber in a compression stroke after a suction refrigerant is introduced and closed, and the discharge bypass port is disposed such that a volume ratio is made smaller in one of the first compression chamber and the second compression chamber having a large amount of the refrigerant injected from the injection port among the first compression chamber and the second compression chamber than in the other one of the first compression chamber and the second compression chamber, the volume ratio being a ratio of the suction volume to the discharge volume of the compression chamber at which the refrigerant in the compression chamber is able to be discharged.
 2. The scroll compressor of claim 1, wherein a check valve that allows flow of the refrigerant to the compression chamber and suppresses flow of the refrigerant from the compression chamber is provided in the injection port.
 3. The scroll compressor of claim 1, wherein an oil reservoir in which oil is stored is formed in a sealed container including the fixed scroll and the orbiting scroll, a high-pressure area and a back-pressure chamber are formed on a rear surface of the orbiting scroll, an oil supplying passage through which the oil is supplied from the oil reservoir to the compression chamber passes through the back-pressure chamber, the oil supplying passage through which the back-pressure chamber communicates with the first compression chamber and the second compression chamber is provided at the position where the injection port is open to the first compression chamber and the second compression chamber during the compression stroke after the suction refrigerant is introduced and closed, and at least a partial section of an oil supplying section in which the oil supplying passage communicates with the first compression chamber or the second compression chamber overlaps with an opening section in which the injection port is open to the first compression chamber or the second compression chamber.
 4. The scroll compressor of claim 2, wherein an oil reservoir in which oil is stored is formed in a sealed container including the fixed scroll and the orbiting scroll, a high-pressure area and a back-pressure chamber are formed on a rear surface of the orbiting scroll, an oil supplying passage through which the oil is supplied from the oil reservoir to the compression chamber passes through the back-pressure chamber, the oil supplying passage through which the back-pressure chamber communicates with the first compression chamber and the second compression chamber is provided at the position where the injection port is open to the first compression chamber and the second compression chamber during the compression stroke after the suction refrigerant is introduced and closed, and at least a partial section of an oil supplying section in which the oil supplying passage communicates with the first compression chamber or the second compression chamber overlaps with an opening section in which the injection port is open to the first compression chamber or the second compression chamber.
 5. The scroll compressor of claim 3, wherein an overlapping section where the oil supplying section overlaps with the opening section is defined as a partial section of the latter half of the oil supplying section.
 6. The scroll compressor of claim 4, wherein an overlapping section where the oil supplying section overlaps with the opening section is defined as a partial section of the latter half of the oil supplying section.
 7. The scroll compressor of claim 1, wherein at least one injection port is provided at a position where the injection port is sequentially open to the first compression chamber and the second compression chamber.
 8. The scroll compressor of claim 1, wherein as the injection port, a first injection port that is open only to the first compression chamber and a second injection port that is open only to the second compression chamber are provided, the first injection port has a larger port diameter than the second injection port, the opening section in which the first injection port is open to the first compression chamber is longer than the opening section in which the second injection port is open to the second compression chamber, or a pressure difference between an intermediate pressure in the first injection port and an internal pressure of the first compression chamber when the first injection port is open to the first compression chamber is more than a pressure difference between an intermediate pressure in the second injection port and an internal pressure of the second compression chamber when the second injection port is open to the second compression chamber. 